Synchrotron radiation photoemission analysis for (NH4)2Sx-treated GaAs

Abstract

The chemistry of the (NH4)2Sx-treated n-GaAs (100) surfaces has been studied using synchrotron radiation photoemission spectroscopy. Ga 3d, As 3d, and S 2p photoemission spectra are measured before and after annealing in vacuum with a photon energy of about 210 eV, where S 2p core level spectra can be sensitively detected. It is found that Ga-S, As-S, and S-S bonds are formed on the as-treated GaAs surfaces, and that stable Ga-S bonds become dominant after annealing at 360 °C for 10 min in vacuum. The thickness of the surface sulfide layer is reduced from about 0.5 to 0.3 nm by annealing. The surface Fermi- level position of the as-treated surfaces is determined to be about 0.8 eV below the conduction band minimum, which is about 0.1 eV closer to the valence band maximum than that of the untreated surfaces. A Fermi-level shift of 0.3 eV toward a flat band condition is also observed after annealing. It is found that the Ga-S bonding plays an important role in passivating GaAs surfaces.

Hf O 2 gate dielectric on (NH4)2S passivated (100) GaAs grown by atomic layer deposition

“…These results suggest that Ga x -S is most thermally stable which is inconsistent with the earlier observations from Sugahara 19 and Spindt 20 . These authors argued that the annealed S-passivated GaAs will leave a gallium rich sulfide terminated surface and the As-S overlayer on GaAs is not completely desorbed until after 250 o C anneal.…”

“…[12][13][14] Although several attempts [9][10][11]15 applied sulfur treatment as a GaAs surface preparations and improved electrical performance for ALD high-k on III-V MOS devices was reported, the bonding arrangement at the sulfide passivated interface with deposited high-k dielectrics has still not been clearly revealed.…”

Improved electrical properties of wafer-bonded p-GaAs/n-InP interfaces with sulfide passivation

“…Surface treatments for III-V compound semiconductor wafers by sulfide compounds were shown to enhance the photoluminescence response and improve the electrical properties by removing the oxygen on the surfaces and reducing the surface trap state densities. [13][14][15][16][17][18] Although this well-known technique has never been employed for direct bonded interfaces, this study shows that the wafers with residual sulfur atoms can be directly bonded without decreasing the bonding strength at the interfaces. In addition, sulfide-passivated interfaces give a significant improvement of the interfacial electrical conductivities and direct bonding of heavily doped p-GaAs and n-InP wafers after sulfide passivation forms a tunnel diode at temperatures as low as 300°C.…”

Chemical bonding and electronic properties of SeS2-treated GaAs(100)

“…The chemical shifts of these peaks, from the As-Ga reference peak, are very close to previously reported values. 23,29,30 The Ga 3d spectrum from the as-treated surface is shown in Fig. 3.…”

“…23,28 The previously reported deconvolution parameters for Se 3d and S 2p were also used. 23,29,30 Table II lists the parameters used for the deconvolution of As 3d, Ga 3d, Se 3d, and S 2p spectra. The experimental data are represented by dots and the solid line by the sum of the simulated components of identical line shape.…”